Peer Revenue Publish or profit

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics

Watch Physics

Tuesday 13 October · still arriving

General Relativity and Quantum Cosmology

Dirac stars in modified $F(R)$ gravity

Zhuldyz Alibekova, Vladimir Dzhunushaliev, Vladimir Folomeev et al. (+1 more)

We study Dirac mini-stars in modified $R^2$ gravity, where gravity is sourced by both linear and nonlinear spinor fields. Two-dimensional (2D) and three-dimensional (3D) profiles of the mini-star mass are constructed as functions of the spinor frequency (for the 2D profiles) and the central value of the spinor field (for the 3D profiles) in general relativity and modified gravity for various values of the spinor nonlinearity parameter. We show that the modification of gravity alters the properties of these configurations, while increasing the nonlinearity parameter within the framework of $R^2$ gravity significantly changes the profiles of the spinor and metric functions, the effective energy density, and the dependence of the total mass on the oscillation frequency. The most pronounced changes occur at large values of the nonlinearity parameter.
Read the full abstract

All authors Zhuldyz Alibekova, Vladimir Dzhunushaliev, Vladimir Folomeev, Sergei Odintsov

Quantum Physics

A complete quantum process model for physically realistic photo-detection in the joint photon-number and spectral degrees of freedom

Sadia Rafi and Aeysha Khalique

Photo-detection is a fundamental component of experimental photonics, yet theoretical models often treat detectors solely in the photon-number basis, neglecting other relevant degrees of freedom such as spectral characteristics. We present a complete quantum process model for physically realistic photodetection that incorporates both photon-number effects and frequency-dependent detector response, described through explicitly derived Kraus operators in the operator-sum representation. This formalism accommodates realistic inefficiencies, models detection within finite spectral windows, and can be directly substituted for idealized models in quantum optical analyses. The model leads to identifying the suitable detection window of the detectors relative to the spectral distribution of incident photons and conversely, in order to maximize the observability of quantum effects.
Read the full abstract

Astrophysics of Galaxies

Massive black holes in the first billion years with JWST

Hannah Übler

The James Webb Space Telescope has unlocked uncharted territory for the study of early black holes, enabling the detection of fainter and smaller black holes at larger cosmological distances than previously possible. Compared to nearby massive black holes, they are characterised by several unexpected attributes, such as their multi-wavelength properties or their relation to their host galaxies. These observational findings challenge our understanding of the past evolution of present-day supermassive black holes, and provide novel anchor points to constrain theoretical models of black hole formation and growth. This review summarises our current understanding of the observed properties of newly discovered, active black holes in the early Universe, discusses the status of mass measurements and the relation to their hosts, as well as open questions and future prospects.
Read the full abstract

Mathematical Physics · Cross-listed from math.SP

Square-Root Profiles and Sharp Fourier Decay of Quasiperiodic Spectral Measures

Zhenfu Wang and Qi Zhou

We study spectral measures of one-dimensional quasiperiodic Schrödinger operators. For subcritical Schrödinger operator with Diophantine frequency, we prove sharp measurable-set bounds, answering a question of Avila and Jitomirskaya \cite{AJ}; we prove optimal Fourier decay and the sharp decay order of the time-averaged quantum return probability, confirming a conjecture of Aloisio, Carvalho, and de Oliveira \cite{ACO} and a prediction of Zhong and Mosseri \cite{ZhongMosseri}. For the subcritical almost Mathieu operator, we establish summable square-root envelopes for the spectral density, with an optimal density-one formulation of the lower bound, thereby answering a question of Avila \cite{Aqi}. These results follow from a general theorem for reflectionless measures under a summable square-root Craig-type condition. We establish an exact residue expansion of the squared Borel transform, which connects local density blow-up with long-time averaged return probabilities: the endpoint residues determine both the square-root edge profiles and the leading coefficient of the time-averaged return probability.
Read the full abstract

Nuclear Theory

Femtoscopic parameters of pion emission sources in EPOS4 Au+Au collisions from 7.7 to 200 GeV

Yan Huang and Máté Csanád

Three-dimensional femtoscopy probes the space-time structure of particle-emitting sources in relativistic heavy-ion collisions. The collision-energy dependence of Lévy source parameters may reveal the evolution of strongly interacting matter and possible signatures of the QCD phase diagram. We previously studied the excitation function of three-dimensional Lévy source parameters for pion pairs in Au+Au collisions with EPOS4, analyzing the pair-distance distribution \(D(\rho)\) through one-dimensional projections. Here, we analyze the full three-dimensional source distribution and correlation function directly. We construct \(D(\rho_{\rm out},\rho_{\rm side},\rho_{\rm long})\) as a 3D histogram, transform it into \(C(q_{\rm out},q_{\rm side},q_{\rm long})\) using a Fast Fourier Transform, and fit the correlation function with the analytic Lévy formula. This approach can reduce biases arising when one-dimensional projections are used to describe a non-elliptical source. We apply the method across the RHIC Beam Energy Scan range and compare the extracted energy dependence with results from the projection-based method and recent UrQMD calculations. We focus on the out-side observables \(R_{\rm diff}^{2}=R_{\rm out}^{2}-R_{\rm side}^{2}\) and \(R_{\rm out}/R_{\rm side}\), whose different energy dependences in EPOS4 and UrQMD may illuminate the roles of emission duration and source dynamics. This work establishes a direct three-dimensional framework for comparison with future femtoscopic measurements and for exploring possible non-monotonic structures associated with the QCD phase diagram.
Read the full abstract

Fluid Dynamics

Preferential concentration of cloud droplets: Coupled effects of phase change and gravitational settling

Zi-Mo Liao

Cloud droplets respond to turbulent motion with finite inertia and settle under gravity, while condensation and evaporation change their sizes. The nonuniform accumulation of cloud droplets in turbulent flows, known as preferential concentration, has attracted sustained interest because it affects droplet collision and coalescence rates. We develop an analytical theory that quantifies the coupled effects of droplet inertia, gravitational settling, and phase change on concentration changes. Applying this theory to simulations of two-dimensional homogeneous thermal convection reveals that phase change markedly enhances preferential concentration in this flow, primarily through spatial differences in settling speed. These differences arise because droplets experience different thermodynamic histories along their trajectories and thus acquire different sizes. Droplet transport further increases this settling contribution by rearranging droplets of different sizes. Fluid deformation partly offsets this enhancement by thinning concentration structures, reducing the preferential concentration measured at a fixed spatial scale.
Read the full abstract

Fluid Dynamics

Partially-Averaged Navier-Stokes simulation of turbulent annular Poiseulle flow

Li-Toong Yap, Marten Klein and Heiko Schmidt

Turbulent annular Poiseulle flow is commonly encountered in various engineering applications, such as heat exchangers. The effects of the inner wall transverse curvature on the flowfield, characterised by the ratio of inner and outer radii $\eta = R_{i}/R_{o}$, have been studied previously using Direct Numerical Simulations (DNS). Scale-resolving simulations based on a Reynolds-Averaged Navier Stokes framework offer a potentially cheaper alternative to traditional Large Eddy Simulations (LES); however it is not clear if such models are able to capture the turbulence anisotropy in the turbulent annular pipe flow. In the present study, turbulent annular Poiseulle flow at $Re_{D_{h}} = 8900$ is performed with the Partially-Averaged Navier Stokes (PANS) model, a variable-resolution turbulence model that is based on the conventional RANS modelling. The ability of the PANS model to capture the effects of the transverse wall curvature is found to be comparable with DNS and other RANS-based scale-resolving approaches despite its relative simplicity and reduced computational cost.
Read the full abstract

Applied Physics

Stability and Optimal Design of Adaptive Linear Bus Holding on Open Chains and Loops

Li Zhen, Weihua Gu, Miny Shen et al. (+2 more)

Bus holding can suppress bunching, but its stability and performance depend on the feedback structure and on how the bus sequence is bounded. This paper develops a common analytical framework for adaptive linear holding on finite open chains and loops and relates both to the bi-infinite system studied in the literature. Matrix and Fourier methods yield necessary and sufficient stability conditions for current- and leading-bus kernels on open chains and general cyclic kernels on loops, together with computable covariance bounds on open chains and exact variance formulas on loops. The analysis shows when periodic closure changes stability, when coefficient-sum stability tests in the literature are conservative, and why a stable open chain can still accumulate substantial variance before boundary effects arrive. For loops with same-lap feedback, modal analysis links control coefficients to fleet-wide schedule drift and to relative headway patterns, explaining the behavior of existing rules and yielding closed-form Pareto-optimal designs for schedule-holding and headway-holding tradeoffs. Cross-lap output corrections relate these designs to physical headway and holding performance. Numerical experiments show that the analytical design and a three-tap approximation, both obtained from closed-form coefficients and a one-dimensional search, outperform four established controls at the tested moderate and loose headway-variance budgets, with holding variances within 0.35% and 3.5% of the full cyclic numerical frontier across these budgets and other parameter variations. The framework thus provides a tractable design procedure and an explanation of how feedback structure and boundary conditions shape service reliability and holding effort.
Read the full abstract

All authors Li Zhen, Weihua Gu, Miny Shen, Wenbo Fan, Feng Xiao

Chemical Physics

Photoinduced Modulation of Rectification and Charge Transport in Diarylethene-Viologen Molecular Junction

Sofyan Tahri, Samuel Decorps, Stephane Lenfant et al. (+2 more)

Large-area molecular junctions combining photochromic and redox-active functionalities provide an attractive platform for controlling charge transport by light. In this work, we study Au/DAEVIO/Ti/Au molecular junctions incorporated with electro-grafted layers of diarylethene-viologen with thicknesses of 12-16 nm. In the initial OFF state, the junctions exhibit low current densities and strong rectification, with a rectification ratio of 300 at 1V. Temperature-dependent measurements reveal a thermally assisted contribution at higher temperatures and a much weaker temperature dependence below 160-180K, consistent with multistep charge transport through molecular and/or interfacial states rather than direct coherent tunneling across the entire molecular layer. Under continuous in situ 385 nm irradiation, the electrical response is strongly and asymmetrically modified. The current density at +1V increases by a factor of 200, while the negative-bias current is only weakly modified, reducing the rectification ratio from 300 to 2. Illumination also produces a nonzero short-circuit current density of + 0.006mA cm-2 and an open-circuit voltage of -0.45V. These results indicate that irradiation simultaneously modifies molecular charge transport and generates a measurable photoelectric response. This behavior is consistent with light-induced changes in electronic coupling associated with DAE photocyclization, combined with photoinduced charge generation and field-dependent charge separation involving the redox-active viologen units and asymmetric electrode interfaces.
Read the full abstract

All authors Sofyan Tahri, Samuel Decorps, Stephane Lenfant, Denis Frath, Imen Hnid

Statistical Mechanics

Molecular-Dynamics Verification of Effective Gravity under Heat Conduction

Satoshi Uruno and Naoko Nakagawa

We test the effective-gravity prediction of global thermodynamics using standard molecular dynamics of a two-dimensional Lennard-Jones fluid. Under weak heat conduction with the lower boundary hotter than the upper boundary, the transition between liquid below gas and liquid above gas shifts from zero to finite downward gravity. Using independently measured equilibrium saturation pressures, we calculate the shift predicted by global thermodynamics and find agreement with the observed transition shift. The transition occurs at zero effective gravity, where the hydrostatic pressure difference balances the saturation-pressure difference between the two boundaries. The hysteresis response under heat conduction also agrees with the equilibrium response when plotted against effective gravity. These results establish the predictive power of global thermodynamics for nonequilibrium structure formation.
Read the full abstract

Quantum Physics

Experimental Benchmarking of a 256-Qubit Room-Temperature NV-Diamond Quantum Processor with an Optically Programmable Biomolecular Quantum Bus

Adams Ivanov, Daniela Herrmann and Erick Giovani Sperandio Nascimento

We report Zeus-256, a room-temperature nitrogen-vacancy (NV) diamond processor with 256 simultaneously active processor-level logical qubits arranged in a 16 x 16 array. Each logical qubit combines an NV electron-spin ensemble with nuclear-spin memory and ancillary resources. OpenQASM 2.0 circuits are transpiled into RFSoC-controlled microwave, radio-frequency, optical, timing, measurement and bus-configuration sequences. An optically programmable proprietary protein-chromophore layer with an internal metastable-triplet spin mediator provides a reconfigurable biomolecular quantum bus for local and long-range interactions. Benchmarks cover QFT, GHZ entanglement, Grover search, arithmetic, variational, neural-network, graph-state and Shor-family circuits. Factor recovery is reported for 11 integers of 8-84 bits, with 10 attempts per instance; the 84-bit endpoint uses 256 qubits and 40,250,342 reported gates, with a reported execution time of 551.694 ms. Bell-CHSH measurements yield S = 2.8008 +/- 0.0446. Three-qubit Grover search returns the marked state in 958 of 1,024 shots (93.55%), compared with an ideal reference of 94.53%. A separate 30,000-shot population-and-parity protocol yields fixed-phase GHZ+ fidelity of 99.8960%, an estimated standard error of 0.2885 percentage points and a conservative physical 95% interval of [98.2342%, 100%]. Timing metrics are partial and do not establish quantum advantage. Scaling to 9,984 processor-level logical qubits is an engineering target, distinct from the demonstrated register.
Read the full abstract

Fluid Dynamics

One-way pressure-independent valves with hysteresis and chattering

Fabio Bagagiolo, Andrea Corli, Stefan Moreti et al. (+1 more)

We propose a model for the one-dimensional isothermal gas flow through a valve in a pipe. The valve aims at keeping the outgoing flow in an assigned interval; moreover, its opening and closing depend on a further parameter. The model is realized by a system of two conservation laws with suitable conditions coupling the ingoing and the outgoing flow. We study the corresponding Riemann problem, where non-classical shocks show up. Although simple, the model allows to study two key oscillatory behaviors of the flow, which are due, respectively, to the chattering of the valve, especially seen in the numerical simulations, and to the stabilizing hysteresis induced by the valve operation. We characterize the states leading to chattering and show how they depend on the parameters of the model. Through several numerical simulations, we study the interplay between the two above phenomena.
Read the full abstract

All authors Fabio Bagagiolo, Andrea Corli, Stefan Moreti, Massimiliano D. Rosini

General Relativity and Quantum Cosmology

Adiabatic particle production in a time-dependent accelerated frame

Victor M Villalba

We study a massive scalar field in flat spacetime written in a time-dependent accelerated frame whose fixed-coordinate observers have maximal proper acceleration at $t=0$ and become asymptotically inertial without forming a horizon. The Klein-Gordon equation separates into a modified Mathieu equation in time and a confining Schrödinger problem in space with a discrete spectrum. We impose an adiabatic vacuum at the instant of maximal acceleration and compute the particle number in the inertial future. For the zeroth-order adiabatic state it falls as the inverse eighth power of the initial mode frequency, and raising the adiabatic order cancels successive terms of the endpoint expansion, in analogy with the switching transients of finite-time detectors. Analytic continuation of the spatial eigenfunctions gives the out modes in closed form and an exact expression for the particle number, which is entirely the mismatch at $t=0$ between the initial state and the out vacuum. The spectrum is algebraic rather than Planckian.
Read the full abstract

Quantum Physics

Autonomous optomechanical Maxwell Demon engine

Sander Stammbach, Giulio Gasbarri and Stefan Nimmrichter

We present a fully autonomous model of a mechanical Maxwell demon engine that converts heat absorbed by a qubit into population inversion in an attached quantum battery. A damped mechanical oscillator acts as a pointer that incorporates the essential demon function of information acquisition about the qubit state and subsequent feedback into the system dynamics, replacing external measurements and control operations. This is achieved by means of a Holstein-type Hamiltonian, which makes the pointer's equilibrium position depend on the qubit state and thereby induces a state-dependent resonance shift. The mechanism enables a selective energy transfer to an attached spin system that acts as the quantum battery. We derive both local and global Lindblad master equations for the coupled system and identify the parameter regimes in which the engine operates efficiently. The figure of merit is the resulting steady-state population inversion of the battery, quantified in terms of ergotropy. Based on these results, we discuss the necessary conditions for practical implementations of the demon engine on realistic experimental platforms.
Read the full abstract

Quantum Physics

Resource-based reliability of quantum-coherent devices

Bowen Sun and D. L. Zhou

Quantum devices can lose the resource needed for a specified function without entering a fixed failure subspace. We propose a resource-based reliability framework for this situation, quantifying the remaining task-relevant resource relative to a stated ideal capacity. The resource measure is selected through its operational connection to the task and the allowed operations. We develop this approach for a trusted quantum random-number generator and a calibrated two-port interferometer. Relative-entropy coherence determines the optimal asymptotic yield of standard coherent qubits under incoherent operations for the former, while logarithmic $l_1$ coherence quantifies the fringe resource of the latter and determines its calibrated correct-port probability. An exactly solvable multi-spin spin-boson model illustrates how environmental records affect these resources at the same isolated-spin dephasing strength. Collective noise preserves coherence within magnetization sectors for product inputs, but enhances the decay of Greenberger-Horne-Zeilinger branch coherence. Finite-record simulations connect the resource definitions to measurement counts and show that increasing the sample size reduces statistical fluctuations without eliminating bias from an incorrect many-spin noise model. The resulting framework provides a task-specific route to reliability assessment when a fixed failure projector is insufficient, while keeping retained resource capacity distinct from a classical survival probability.
Read the full abstract

High Energy Physics (Phenomenology)

Signature of GW from the Hidden Sector in light of the Recent LZ Event

Sujit Kumar Sahoo, Narendra Sahu and Vicky Singh Thounaojam

The LZ collaboration has recently reported a single nuclear-recoil event at $E_R=248\pm23_\text{stat}\pm23_\text{sys}$ keV, observed in a 2.84 tonne-year exposure with a local significance of $3.4\sigma$, pointing towards an inelastic dark matter (DM) interpretation. We explain this event within a gauged $U(1)_X$ hidden-sector model, spontaneously broken by a singlet scalar whose vacuum expectation value (VEV) gives rise to: (i) gauge boson mass, (ii) a small Majorana mass for the vector-like singlet fermion, the DM candidate, charged under the new symmetry, which splits the fermion into two pseudo-Dirac states (mass splitting proportional to the scalar VEV) thus resulting in a purely off-diagonal vector current, (iii) the frequency and the amplitude of the GW signal arising from the hidden sector symmetry breaking via first-order phase transition (FOPT). The symmetry-breaking scale thus provides a multi-messenger probe connecting terrestrial direct-detection kinematics at the LZ and early-universe FOPT thermodynamics while obtaining thermal DM relic abundance. We delineate the viable parameter space compatible with the LZ event, correct relic density, and detectable GW signals in the low frequency regimes at future interferometers like $\mu {\rm ARES}$ and THEIA while satisfying existing cosmological, astrophysical, and terrestrial bounds.
Read the full abstract

Quantum Physics

PPVM: A Circuit Simulation Framework for Digital Twins of Quantum Processors

Xiu-Zhe Luo, David Plankensteiner, Kai-Hsin Wu et al. (+12 more)

Quantum computers are approaching the early fault-tolerant regime. Verifying the next generation of quantum hardware requires joint emulation of the quantum processor, hardware noise, and classical control and decoding logic. We introduce the Programmable Pauli Virtual Machine (PPVM), an open-source framework for digital twins of quantum processors. PPVM unifies Pauli propagation and generalized tableau simulation under a common abstraction within a single virtual machine. Its bytecode supports arbitrary classical control flow, with measurement-conditioned feed-forward available in the generalized tableau backend. For neutral-atom hardware, we derive independent and correlated atom-loss channels and integrate them into both backends. We demonstrate loss-aware magic state distillation on over a thousand physical qubits and integration with classical decoding through Bloqade QEC Studio.
Read the full abstract

All authors Xiu-Zhe Luo, David Plankensteiner, Kai-Hsin Wu, Rob Patterson, Alexander Schuckert, Oriol Rubies-Bigorda, Refaat Ismail, Jonhas Colina, Neelay Fruitwala, Danylo Lykov, Tyson Jones, Stefan Krastanov, Rafael Haenel, Stefan Ostermann, Sheng-Tao Wang

Mesoscale and Nanoscale Physics

Zeeman spin quantum geometry and intrinsic gyrotropic spin current

Srijan Chatterjee and Tarun Kanti Ghosh

We uncover an intrinsic gyrotropic spin current (IGSC) driven solely by an oscillating magnetic field, arising from the spin version of Zeeman quantum geometry. Using the density matrix formalism, we derive the IGSC in the low-frequency clean limit, in terms of the Zeeman spin quantum metric and the Zeeman spin Berry curvature. The effect is studied in a minimal Rashba-Dresselhaus model that also supports intrinsic gyrotropic charge currents from the Zeeman Berry curvature. The spin and charge currents exhibit a $\pi/2$ phase shift and are found to be perpendicular to each other for certain parameter ranges. This not only enables spin current detection but also opens pure spin current channels for energy-efficient spintronics. We further observe that these currents switch directions between longitudinal and transverse relative to the applied field, depending on the relative strength of Rashba and Dresselhaus interactions.
Read the full abstract

Instrumentation and Detectors

Cryogenic characterisation of the FBK NUV-HD-cryo Silicon Photomultipliers for the DarkSide-20k dark matter experiment

F. Acerbi, P. Adhikari, P. Agnes et al. (+299 more)

Liquid Argon Time Projection Chambers (TPCs) are highly promising detectors for dark matter searches due to their uniform response, scalability to large target masses, and compatibility with ultra-low background conditions. The DarkSide-20k (DS-20k) experiment, currently under construction at Istituto Nazionale di Fisica Nucleare (INFN) Laboratori Nazionali del Gran Sasso (LNGS), aims to achieve unprecedented sensitivity to Weakly Interacting Massive Particles (WIMPs), approaching the neutrino fog. At the heart of the detector is a dual-phase TPC filled and surrounded by low-radioactivity argon from underground sources (i.e. Underground Argon (UAr)), functioning both as the WIMP target and detection medium. The experiment employs Fondazione Bruno Kessler (FBK) NUV-HD-cryo Silicon Photomultipliers (SiPMs) as the chosen photon sensors for its optical planes. Key SiPM properties such as dark noise rate, gain and direct crosstalk were measured using specialized test setups at 77 K. The photon detection efficiency (PDE) was measured under vacuum at 77 K over the wavelength range 350-820 nm. Secondary photon emission, which can give rise to external optical crosstalk, was measured under vacuum at 86 K over the wavelength range 550-1020 nm.
Read the full abstract

All authors F. Acerbi, P. Adhikari, P. Agnes, I. Ahmad, S. Albergo, I. F. Albuquerque, T. Alexander, A. K. Alton, P. Amaudruz, G. A. Anastasi, M. Angiolilli, E. Aprile, D. J. Auty, M. Ave Pernas, O. Azzolini, H. O. Back, Z. Balmforth, A. Barrado Olmedo, P. Barrillon, G. Batignani, S. Bharat, P. Bhowmick, S. Blua, V. Bocci, W. Bonivento, B. Bottino, M. G. Boulay, T. Braun, A. Buchowicz, J. Busto, M. Cadeddu, M. Cadoni, R. Calabrese, V. I. Calì, A. Caminata, N. Canci, M. Caravati, M. Cardenas-Montes, N. Cargioli, M. Carlini, L. Castellani, P. Castello, D. F. F. S. Cavalcante, P. Cavalcante, S. Cebrian, A. Chepurnov, L. Cifarelli, Y. Coadou, I. Coarasa, V. Cocco, E. Conde Vilda, L. Consiglio, H. Coombes, A. F. V. Cortez, B. S. Costa, P. A. Costa e Silva, M. Czubak, S. D'Auria, M. D. Da Rocha Rolo, A. Dainty, G. Darbo, S. Davini, R. de Asmundis, S. De Cecco, M. De Napoli, G. Dellacasa, A. Derbin, L. Di Noto, P. Di Stefano, D. Díaz Mairena, C. Dionisi, G. Dolganov, F. Dordei, A. Elersich, E. Ellingwood, T. Erjavec, N. Fearon, M. Fernandez Diaz, L. Ferro, A. Ficorella, G. Fiorillo, D. Fleming, L. Flores, P. Franchini, D. Franco, H. Frandini Gatti, F. Gabriele, D. Gahan, C. Galbiati, G. Galiński, G. Gallina, M. Garbini, P. Garcia Abia, A. Gawdzik, G. K. Giovanetti, A. Gola, L. Grandi, G. Grauso, G. Grilli di Cortona, A. Grobov, M. Gromov, J. Guerrero Cánovas, M. Gulino, S. B. Habtemariam, B. R. Hackett, A. Hallin, M. Haranczyk, T. Hessel, C. Hidalgo, J. Hollingham, S. Horikawa, J. Hu, F. Hubaut, D. Huff, T. Hugues, A. Ianni, A. Ianni, V. Ippolito, A. Jamil, C. Jillings, P. Kachru, R. Keloth, N. Kemmerich, A. Kemp, K. Kondo, G. Korga, L. Kotsiopoulou, S. Koulosousas, P. Kunze, M. Kuss, M. Kuźniak, M. Kuzwa, M. I. Kwon, M. La Commara, M. Lai, E. Le Guirriec, E. Leason, A. Leoni, L. Lidey, J. D. Lipp, L. Lippolis, M. Lissia, L. Luzzi, O. Lychagina, O. Macfadyen, J. Machts, I. Machulin, S. Mameli, S. Manecki, I. Manthos, A. Marasciulli, S. M. Mari, C. Mariani, J. Maricic, M. Martinez, G. Matteucci, K. Mavrokoridis, A. Mazzi, A. B. McDonald, L. Meng, A. Messina, R. Milincic, G. Miller, S. Minutoli, A. Mitra, J. Monroe, M. Morrocchi, A. Morsy, V. Muratova, M. Murra, C. Muscas, P. Musico, R. Nania, M. Nessi, G. Nieradka, K. Nikolopoulos, E. Nikoloudaki, J. Nowak, K. Olchanski, A. Oleinik, P. Organtini, A. Ortiz de Solórzano, A. Padmanabhan, M. Pallavicini, L. Pandola, E. Pantic, E. Paoloni, D. Papi, L. Parellada Monreal, B. Park, G. Pastuszak, G. Paternoster, R. Pavarani, A. Peck, P. A. Pegoraro, K. Pelczar, R. Perez, V. Pesudo, S. Piacentini, N. Pino, G. Plante, A. Pocar, S. Pordes, P. Pralavorio, E. Preosti, D. Price, G. Prior, M. Pronesti, S. Puglia, M. Queiroga Bazetto, F. Raffaelli, F. Ragusa, Y. Ramachers, A. Ramirez, S. Ravinthiran, K. Raymond, M. Razeti, A. L. Renshaw, A. Repond, M. Rescigno, S. Resconi, F. Retiere, A. Ritchie-Yates, A. Rivetti, A. Roberts, C. Roberts, D. Rodríguez Rodas, G. Rogers, L. Romero, M. Rossi, D. Rudik, J. Runge, M. Sabia, C. Salerno, P. Salomone, O. Samoylov, S. Sanfilippo, D. Santone, R. Santorelli, E. M. Santos, I. Sargeant, M. L. Sarsa, C. Savarese, E. Scapparone, D. Semenov, C. Seoane, A. Serrecchia, M. Sestu, V. Shalamova, S. Sharma Poudel, A. Sheshukov, M. Simeone, D. Sitzia, P. Skensved, M. Skorokhvatov, O. Smirnov, T. Smirnova, B. Smith, F. Spadoni, M. Spangenberg, A. Steri, M. R. Stock, V. Stornelli, S. Stracka, A. Sung, C. Sunny, Y. Suvorov, A. M. Szelc, O. Taborda, B. Tam, R. Tartaglia, A. Taylor, J. Taylor, G. Testera, A. Thompson, S. Torres-Lara, A. Tricomi, S. Tullio, E. Unzhakov, M. Van Uffelen, P. Ventura, G. Vera Díaz, S. Viel, A. Vishneva, R. B. Vogelaar, J. Vossebeld, B. Vyas, M. Wada, M. Walczak, Y. Wang, S. Westerdale, L. Williams, M. M. Wojcik, M. Wojcik, Z. Xu, J. Yin, A. Zabihi, P. Zakhary, A. Zani, H. Zhan, Y. Zhang, G. Zuzel

Materials Science

MINFF: A Family of Classical Force Fields for Minerals with Tunable Angle Terms

Michael Holmboe, Nathan Lavauzelle and Rogers E. Swai

Atomistic simulations of minerals are limited by the accuracy and transferability of the force field. We introduce MINFF, a force field family for layered and non-layered oxides and hydroxides of M being Si, Al, Fe, Mg, Ca, Ti, Li and F. MINFF has no M-O bond terms. Instead M-O distances follow from electrostatics and dispersion, while a single harmonic angle term on all M-O triplets controls coordination geometry. Metal charges are DDEC6 charges from reference mineral structures, and oxygen charges are assigned by nearest-neighbour charge smearing, covering basal, apical, hydroxyl and edge sites and sites adjacent to isomorphous substitutions. The oxygen Lennard-Jones parameters are based on the OPC3 water model and change by less than 5% when re-optimised per mineral, so compatibility with OPC3 and related ion-pair potentials is measured rather than assumed. Metal Lennard-Jones parameters were fitted to unit-cell metrics, bond distances and angles, both synchronously across more than 30 reference minerals (general, GMINFF) and for individual minerals (tailored, TMINFF), each at four angle force constants (0, 250, 500 and 1500 kJ/mol/rad^2). With angle terms, MINFF reproduces experimental unit-cells metrics to within 0.5% and atom-type distances and angles to within 0.7-1.4% and 0.1-0.4%, with Global Instability Index values as low as 0.11, below those of CLAYFF (0.34) and INTERFACE (0.21). A moderate angle constant reproduces the stiff in-plane and soft shear elastic constants of phyllosilicates and improves the Kaolinite librational bands, and in hydrated Na-Montmorillonite MINFF gives the lowest residual factor against the 2W 00l pattern of the models tested. The general and tailored sets at four angle stiffnesses give direct control over the transferability-fidelity trade-off. Topologies can be generated with the atom (MATLAB) and atomipy (Python) libraries and at www.atomipy.io.
Read the full abstract

2610.18220 · 13 Oct · 63 pages, 7 figures and 3 tables in the main text. Supporting information (included in the same file) has 19 pages with 9 figures and 5 tables. Parameters, reference structures, misc. scripts and topology generators available via https://github.com/mholmboe/minff and https://www.atomipy.io

Abstract PDF $CELL ×2$TOPO ×1

Quantum Physics

Methods for Automated Equivalence Checking of Quantum Error-Correction Codes

Maxie Bichmann, Ludwig Schmid and Robert Wille

Quantum error-correction code and circuit construction is an active field of research, motivating automated methods for identifying equivalent designs. We develop and evaluate automated strategies for deciding whether two descriptions of quantum error-correction codes are equivalent under specified transformations. We formalize permutation equivalence for stabilizer and CSS codes and local-Clifford equivalence for stabilizer codes within a unified framework that separates physical from representation freedom. We develop three decision strategies (group-action search, isomorphism-based methods, and constraint solving), together with invariants and signatures for preprocessing. The empirical evaluation shows that no paradigm dominates across equivalence notions, code families, and parameter ranges. We therefore combine their complementary strengths in input-dependent hybrid checkers following a staged Refute-Refine-Decide architecture. Mean hybrid runtimes remain below 10 s for most evaluated structured-code cases with $n \leq 37$; for inequivalent code instances with $n=144$, they are about 310 s for permutation and 16 s for local-Clifford equivalence.
Read the full abstract

Nuclear Theory

Exact solution of adiabatic time dependent Hartree-Fock-Bogoliubov inertia for fission

C.V. Nithish Kumar, Gabriel Martínez-Pinedo, Samuel A. Giuliani et al. (+1 more)

An efficient method to exactly compute the adiabatic time-dependent Hartree-Fock-Bogoliubov collective vibrational inertias typical of fission is proposed. The method uses the quasiparticle finite amplitude method to invert the stability matrix of linear response. A comparison with other approaches, such as the exact generator coordinate method inertia and the associated cranking non-perturbative approximation, is conducted. It is found that the behaviour as a function of the collective variable (mass quadrupole moment) is essentially the same in the four cases considered, and substantially differs from the commonly used perturbative approach. It is also found that the magnitudes of the inertias are to a good extent related by single factors that seem to be connected with the effective mass of the energy density functional used.
Read the full abstract

All authors C.V. Nithish Kumar, Gabriel Martínez-Pinedo, Samuel A. Giuliani, Luis M. Robledo

Strongly Correlated Electrons

Unexpected stabilization of a single-$q$ charge density wave in pristine 1T-TiSe$_2$

Kimoon Higashihira Han, Dongju Hwang, Dongsin Kim et al. (+16 more)

Over the past decade, studies revisiting the classical charge-density-wave system 1T-TiSe$_2$, long understood to host the $2 \times 2$ triple-$q$ order with equivalent subcomponents, have suggested that these subcomponents may not be identical, challenging a 50-year-old paradigm. Here, we demonstrate not only that these subcomponents are non-identical but also that they develop sequentially rather than simultaneously. By tracking folded-band features, angle-resolved photoemission spectroscopy reveals that a unidirectional $2 \times 1$ single-$q$ order stabilizes first, while the other two components emerge sequentially at lower temperatures, completing the triple-$q$ phase. Our free-energy analysis explains this hierarchy through repulsive coupling among the three subcomponents, as supported by first-principles calculations incorporating phonon anharmonicity. Consequently, the three subcomponents are inequivalent in both phase and amplitude. These results reconcile reported symmetry breaking and differing characteristic temperatures and establish a framework in which ostensibly simple, high-symmetry charge-density order emerges from temperature-dependent competition and cooperation among inequivalent subcomponents.
Read the full abstract

All authors Kimoon Higashihira Han, Dongju Hwang, Dongsin Kim, Yeojin Ahn, Jaehun Cha, Seonggeon Gim, Gyubin Lee, Mingi Jho, Chan-young Lim, Sae Hee Ryu, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Jonathan D. Denlinger, Makoto Hashimoto, Donghui Lu, Young Woo Choi, Gil Young Cho, Yeongkwan Kim

High Energy Astrophysical Phenomena

Fast Radio Bursts from Monster Shocks and Flares of Inspiraling Binary Neutron Stars: A Kinetic Model for Double Pulsar

Jan Benáček, Benoît Cerutti, Martin Pohl et al. (+2 more)

The coalescence of binary neutron star systems offers unprecedented possibilities for multimessenger observations, including the detection of gravitational waves, gamma-ray bursts, kilonovae, and potentially fast radio bursts. For a detailed investigation of the latter, one requires a kinetic plasma model to describe the interacting magnetospheres of the stars. We present a three-dimensional particle-in-cell kinetic simulation of the combined magnetosphere of a binary neutron star in which the two stars physically orbit one another so that the orbital motion itself twists the magnetic loops. We find that the stellar magnetic-field intensity ratio controls the emergence of flares, while the stellar spins set the direction and modulation of the flare. We identify four spatially and dynamically distinct regions of strong electromagnetic energy release: (i) an expanding fast magnetosonic wave that steepens into a monster shock, (ii) a plasma flare being pushed by (iii) an expanding fireball and containing (iv) a reconnecting current sheet. The fast magnetosonic wave is a promising source of coherent radio emission. It is released when orbital motion cuts a closed plasma loop. The electric and magnetic wave amplitudes are similar and reach that of the background magnetic field. Our kinetic treatment yields particle spectra and plasma structures that can be used to assess coherent emission in kinetic-scale simulations. In conclusion, the stellar orbital motion constitutes a driving channel distinct from models with spin-driven magnetospheric twisting.
Read the full abstract

All authors Jan Benáček, Benoît Cerutti, Martin Pohl, Tim Dietrich, Anna Neuweiler

Medical Physics · Cross-listed from math.NA

Hyperelastic Modeling of Cardiac Tissue Deformation for Data Registration

Joyce Ghantous, Yves Coudiere and Michael Leguèbe

This work proposes a biomechanical registration framework designed to combine functional optical-mapping data with structural high-resolution MRI of cardiac tissue. The two acquisitions are performed in different mechanical configurations: optical mapping is obtained after stretching the sample, whereas MRI is acquired in a fixed resting state. To estimate the deformation between these configurations, the tissue is modeled as a nearly incompressible transversely isotropic hyperelastic material, and the traction amplitude is identified from optical-map marker positions through an inverse problem. Two-and threedimensional simulations show physically admissible deformations and provide a first proof of concept for the proposed strategy.
Read the full abstract

Optics

Optical parametric amplification of spatiotemporal optical vortices

Houan Teng, Chenhao Wan and Qiwen Zhan

Spatiotemporal optical vortices (STOVs) are structured light featuring a phase singularity in the spatiotemporal domain, exhibiting unique topology that couples spatial and temporal dimensions. To date, amplification of STOVs remains unexplored, and their wavelength tunability is limited by available light sources. In this work, we present the theoretical analysis and experimental demonstration of optical parametric amplification (OPA) of STOVs. The pulse energy of the STOV signal is enhanced by a factor of 60, while its spatiotemporal structure is robustly preserved. The generated idler inherits the phase-conjugated STOV topology with the opposite topological charge, governed by simultaneous conservation of energy, linear momentum, and spatiotemporal orbital angular momentum. The intrinsic wavelength-conversion capability of OPA further provides a route towards spectrally tunable STOV generation, spanning from visible to near-infrared wavelength regimes. This work paves the way toward further development of multi-stage amplification architectures, facilitating applications of wavelength-tunable spatiotemporally structured light at ultrahigh intensities.
Read the full abstract

Quantum Physics

Theory of Trotter Error with Variable-Weight Schedules

Henrique Ennes

Trotterization is a widely used algorithm for simulating quantum evolutions and consists of approximating a target unitary through a local linear decomposition of its generator that is repeated over $N$ steps. We introduce {scheduled trotterization}, a variable-weight modification in which the coefficients of the local linear decomposition are allowed to change from step to step. Using the geometry of the Lie group of unitary operators, we express the global endpoint error as a product of transported local defects, whose leading terms are obtained by two applications of the Baker-Campbell-Hausdorff formula, one inside each local step and one between different transported defects, separating the internal Trotter error from the external accumulation error. While we recover recent tighter bounds on the global approximation error when the weights are held fixed, the new framework allows us to propose a weight-varying schedule that significantly decreases the global error. For exact infinitesimal synthesis, we prove that this improves the usual fixed-weight $O(N^{-1})$ behavior to $O(N^{-2})$, without changing the basic pulse skeleton. We also extend the framework to imperfect infinitesimal synthesis, as arises in quantum gate synthesis problems, where admissible coefficients may only approximate the desired local corrections. In this case, the error is controlled by a local covering parameter measuring the quality of the available coefficient set. Numerical experiments for random $\SU(2)$ targets further support the predicted theoretical improvements. The results suggest a novel perspective for the analysis of Trotter errors, which can be treated as schedulable quantities to be coherently canceled at the endpoint.
Read the full abstract

Optics

Feedback-Controlled Self-Trapping of Solitons

Raonaqul Islam, Pradyoth Shandilya, Yunxiang Song et al. (+5 more)

Chip-scale microresonator-based frequency combs, commonly referred to as microcombs, are promising sources for field-deployable metrology applications. However, intrinsic microresonator noise can make it difficult to generate microcombs with sufficiently low noise for applications. A widely used approach to overcome this limitation is to trap the DKS in the microresonator by phase-modulating the pump laser, although integrating a low-noise modulation reference in a fully on-chip platform remains challenging. Here, we propose an optoelectronic self-trapping scheme in which the impact of intrinsic microresonator noise on microcomb repetition-rate jitter is suppressed through feedback-controlled phase modulation of the driving laser so that the intrinsic noise of the laser sets the ultimate performance limit. This modification eliminates the need for an external low-phase-noise RF source, thereby enabling chip integration. We develop both analytical and numerical models for the proposed system and benchmark its performance against conventional externally referenced bulk implementations, showing that the proposed approach achieves comparable microcomb noise suppression while maintaining chip-scale compatibility.
Read the full abstract

All authors Raonaqul Islam, Pradyoth Shandilya, Yunxiang Song, Alioune Niang, Gary Carter, Thomas Carruthers, Curtis Menyuk, Ergun Simsek

Plasma Physics

Controlling writhe in stellarator optimization

Tobias M. Schuett and Sophia A. Henneberg

The writhe of a closed curve measures its coiling, and for a ribbon along it, writhe is the contribution to the linking number not due to twist. In stellarators, large writhe implies large helical excursion and has previously been either an uncontrolled outcome in optimization, or fixed beforehand by the choice of the coordinate system. We present a simple method to target the underlying writhe of the plasma boundary during optimization. Our method calculates writhe and linking number directly from the underlying elliptical boundary of the stellarator. It therefore does not require any properties of the MHD equilibrium solve, such as the true magnetic axis, making it fast to evaluate and smooth to differentiate. Examples for quasi-helically symmetric stellarators show that this target works well in practice.
Read the full abstract

Superconductivity

Quantitative Impact of Occupation Smearing Methods on Conventional Superconductivity: from Electronic Structure through Lattice Dynamics to Electron-Phonon Coupling

Zhongyu Wan

In first-principles calculations of metallic systems, the discrete electronic mesh in the Brillouin zone necessitates a smearing function and its width (e.g., the widely used 0.02 Ry Methfessel-Paxton scheme) to enforce continuity of energy and occupation at the Fermi surface. However, the quantitative impact of such empirical parameters on phonon-mediated superconductivity has long been overlooked, leading to their habitual selection by mere convention. Here, using hexahydride CsH6 as a benchmark, we systematically investigate the magnitude and propagation mechanism of smearing-induced errors against the parameter-free optimized tetrahedron method. Long-tailed smearing delocalizes the occupation window, causing substantial Fermi-level shifts, flattening of the density of states, and hardening phonon modes, thereby weakening electron-phonon coupling. Conversely, short-tailed smearing suffers from insufficient sampling, producing density-of-states oscillations and enhanced Fermi-surface nesting; via amplified electronic screening and Peierls instabilities, this softens acoustic modes and generates imaginary frequencies, causing CsH6 to be dynamically unstable and discarded. However, the optimized tetrahedron method reveals that CsH6 is dynamically stable under ambient pressure with a remarkable superconducting transition temperature of 121 K. To prevent subjective empirical parameters from obscuring theoretically promising high-temperature superconductors, we derive a simple scaling relation for the smearing width, applicable to different smearing functions, from the free-electron-gas model, offering an objective, precise, and efficient protocol for parameter selection in high-throughput screening.
Read the full abstract